title: Orientation with a Viking sun-compass, a shadow-stick, and two calcite sunstones under various weather conditions.
abstract: It is widely accepted that Vikings used sun-compasses to derive true directions from the cast shadow of a gnomon. It has been hypothesized that when a cast shadow was not formed, Viking navigators relied on crude skylight polarimetry with the aid of dichroic or birefringent crystals, called "sunstones." We demonstrate here that a simple tool, that we call "shadow-stick," could have allowed orientation by a sun-compass with satisfying accuracy when shadows were not formed, but the sun position could have reliably been estimated. In field tests, we performed orientation trials with a set composed of a sun-compass, two calcite sunstones, and a shadow-stick. We show here that such a set could have been an effective orientation tool for Vikings only when clear, blue patches of the sky were visible.
authors.forename: Balázs
authors.initials: B
authors.lastname: Bernáth
authors.forename: Miklós
authors.initials: M
authors.lastname: Blahó
authors.forename: Adám
authors.initials: A
authors.lastname: Egri
authors.forename: András
authors.initials: A
authors.lastname: Barta
authors.forename: György
authors.initials: G
authors.lastname: Kriska
authors.forename: Gábor
authors.initials: G
authors.lastname: Horváth
mesh_terms: D002119:Calcium Carbonate / Q000737:chemistry*; D060526:Magnetic Fields; D009949:Orientation; D012031:Refractometry / Q000295:instrumentation*; D062211:Spatio-Temporal Analysis; D013472:Sunlight; D014887:Weather
chemical_list: D002119:Calcium Carbonate